Marine Weather Net

Southwestern Puerto Rico out 10NM Marine Forecast


REST OF TODAY

E
WINDS
10 - 15
KNOTS

TONIGHT

E
WINDS
5 - 10
KNOTS

MONDAY

E
WINDS
10 - 15
KNOTS

MONDAY NIGHT

E
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
AMZ745 Forecast Issued: 957 AM AST Sun Sep 25 2022

Rest Of Today...East Winds 10 To 15 Knots. Seas 1 To 3 Feet. Dominant Period 10 Seconds. Isolated Thunderstorms This Afternoon.
Tonight...East Winds 5 To 10 Knots. Seas 1 To 3 Feet. Dominant Period 8 Seconds. Isolated Showers.
Monday...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 10 Seconds. Isolated Thunderstorms In The Afternoon.
Monday Night...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 10 Seconds. Isolated Showers.
Tuesday...East Winds 10 To 15 Knots. Seas 1 To 3 Feet. Dominant Period 10 Seconds. Isolated Showers.
Wednesday...East Winds 5 To 10 Knots. Seas 1 To 3 Feet. Dominant Period 10 Seconds, Subsiding To 8 Seconds. Isolated Thunderstorms Through The Day. Scattered Showers.
Thursday...East Winds 5 To 10 Knots. Seas Around 2 Feet Or Less. Dominant Period 7 Seconds. Scattered Showers.
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Area Forecast Discussion
National Weather Service San Juan PR
1103am AST Sunday September 25 2022

...New

Issued at 1031am AST Sunday September 25 2022

Isolated showers were occurring in the local waters with one or two showers in southeast Puerto Rico under mostly sunny skies. Convection in western Puerto Rico as well as around or downstream of the U.S. Virgin Islands still expected. Very few changes have been made to the forecast grids. The morning sounding from San Juan Puerto Rico at 25/12Z showed a mostly moist profile with a precipitable water of 1.91 inches and a moderate CAPE of 2327 J/Kg.

Synopsis
Instability will gradually increase this week, with a higher chance of shower and thunderstorm formation each afternoon. Urban and small stream flooding will remain a concern each day, especially along the interior and western municipalities of Puerto Rico.

.SHORT TERM...Today through Tuesday... A gradually eroding mid to upper level ridge aloft will be replaced by a TUTT low which will relocate just north of the region today, then further strengthen and linger across the northeastern Caribbean through Tuesday. This will favor increasing instability aloft on Monday and Tuesday. A surface high pressure ridge will build and spread westwards across the western and southwest Atlantic during the period, to maintain a moderate east southeast wind flow across the area. A broad weakly induced surface trough is forecast to cross the region later tonight through Tuesday, bringing a slight increase in tropical moisture and low level convergence.

For today although an overall drier pattern is expected, a few passing showers will continue to affect the coastal waters the rest of the early morning. This will be followed by a seasonal weather pattern with isolated to scattered shower development mainly over parts of the interior and west sections Puerto Rico. Ponding of water on roads and minor, urban an small stream flooding will remain possible with the heaviest rains in west PR. Elsewhere mostly fair skies are forecast with only a few showers expected to develop in and around the U.S. Virgin islands and adjacent islands. However, most of the showers, if any, should be mainly on the west-end or just downwind of the islands.

For Monday and Tuesday, the instability aloft caused by the repositioning of the TUTT, along with increasing moisture convergence created by the surface trough, will all favor a better chance for increasing frequency of passing morning showers, followed by some enhanced afternoon convection in and around the islands especially over parts of the interior and west sections of Puerto Rico including the San Juan Metro, where urban and small stream flooding will again be likely, as well as ponding of water on roads in poor drainage area with the heaviest rains.

Long Term
Wednesday through Monday... Another upper level low will detach from a wide Tropical Upper Tropospheric Trough localed over the central Atlantic, and then the low will approach the northeastern Caribbean on Wednesday. At the surface, moisture will increase due to patches of air with higher relative humidity induced by the upper level system that continue to be dragged across the area by the trade winds. As a result of the the upper level support and the low level moisture, active afternoons are expected across the area, with advective showers moving across eastern Puerto Rico and the United States Virgin Islands during the day, and afternoon convection developing across the interior and western Puerto Rico. The islands will be under the influence of the upper level trough through Friday. Then, on Saturday, a mid level ridge tries to build in north of the region. At the same time, moisture will be pulled out from the ITCZ (Intertropical Convergence Zone) across the northeastern Caribbean. With this deep-layered moisture, the wetter pattern will be stretching into the upcoming weekend, with an elevated risk of flooding, water surges along rivers and mudslides in areas of steep terrain.

Marine
No changes were made to the marine forecast. Seas will remain at five feet or less with winds out of the east at 10 to 15 knots. There is a moderate rip current risk for the local beaches.

.SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None.